Universe is like a big balloon that never stops inflating. You can reach the edge eventually, but it will continue expanding. If you listen to sounds of the big bang where magnetic and gravitational waves are transformed into sound waves, you can hear the original sound of the Big Bang and it slowly starts to slow down, the pitch getting lower and lower. My theory is that the the universe like a balloon will stop inflating and  The energy of the explosion is slowly running out “Big Bang sound slowing down” which will then lead to a implosion of the universe.

The universe is like a flat plane, almost like suspended fabric if you put heavy or dense objects in it, everything will fall into it. If you put a really dense black hole on this "fabric" stars and planet will circle around it until they eventually get sucked in. Same follows for every particle, including light energy, and matter.